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Citation for Study 1186

About Citation title: "A new brown algal order, Ishigeales (Phaeophyceae), established on the basis of plastid protein-coding rbcL, psaA, and psbA region comparisons.".
About This study was previously identified under the legacy study ID S1095 (Status: Published).

Citation

Cho G., Lee S., & Boo S. 2004. A new brown algal order, Ishigeales (Phaeophyceae), established on the basis of plastid protein-coding rbcL, psaA, and psbA region comparisons. Journal of Phycology, null.

Authors

  • Cho G.
  • Lee S.
  • Boo S.

Abstract

The brown algal family Ishigeaceae currently includes a single genus, Ishige Yendo, with two species, which inhabit the warm waters of Korea, China, Japan, and the northeastern Pacific coast of America. The relationship of the family to other brown algal lineages is less studied in terms of their plastid ultrastructure and molecular phylogeny. We determined the sequences of rbcL from four samples of the two Ishige species and nine putative relatives, and the sequences of psaA and psbA sequences from 37 representatives of the brown algae. Analyses of the rbcL, psaA, psbA, and rbcL + psaA + psbA data sets resulted in similar trees, however, the concatenated data gave greater resolution and clade support than each individual gene. In all the phylogenies reconstructed from individual and combined data sets, the Phaeophyceae was well resolved, the Ectocarpales being placed in a terminal position, and the Ishigeaceae ending up in a basal position. The exclusion of the Ishigeaceae from the Ectocarpales s.l. or putative relatives was supported by the Shimodaira-Hasegawa tests, using the combined data set. From our ultrastructural study, we concluded that the pyrenoid is absent in the Ishigeaceae, despite the presence of a rudimentary pyrenoid in I. okamurae. These results suggest that the Ishigeaceae, sharing apical growth, pyrenoidless plastids, and isomorphic life history with most of basal brown algae, is an early-diverging brown lineage. Our molecular and morphological data, therefore, lead us to exclude the Ishigeaceae from the Ectocarpales s.l., which have an elaborate pyrenoid, and to propose its own order Ishigeales ord. nov. The order Ishigeales is distinguished by oligostichous structure of thalli, phaeophycean hairs formed within cryptostomata, unilocular sporangia transformed from terminal cortical cells, and plurilocular sporangia lacking sterile terminal cells. This study is the first to document the utility of the psaA and psbA sequences for phylogenetic studies of brown algae and also the first report on the multigene phylogeny of the Phaeophyceae based on three protein-coding plastid genes.

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  • Canonical resource URI: http://purl.org/phylo/treebase/phylows/study/TB2:S1186
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